I don't have the code posted by Giovanni but this is very easy to do with Shapely <http://toblerity.org/shapely/manual.html> (a Python wrapper of GEOS).
With PyQGIS, I do it in this way: 1) by definition a polyline is composed of straight segments between points (nodes) 2) after computing the intersection between the polylines , the intersecting point lies on a particular segment, easy to determine. 3) Then a simple loop through the segments (length) allows to compute the distance between the first point of the line and the intersection point (= sum of segments length + the length of the segment between the first point of the segment where the intersecting point lies and the intersection point). -- View this message in context: http://osgeo-org.1560.x6.nabble.com/calculate-distance-from-two-points-along-line-in-pyqgis-tp5181313p5181413.html Sent from the Quantum GIS - Developer mailing list archive at Nabble.com. _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
